Comparing the Impacts of Drought

When the demand for water exceeds the available amount during a certain period, or when poor quality restricts its use, a region experiences water stress. Human activities can make this worse through positive feedback loops. For example, deforestation and overgrazing reduce soil moisture and evapotranspiration, which in turn reduces rainfall and worsens the drought.

Comparing Impacts: Developed vs. Emerging Countries

The same lack of rain can cause a price rise in one country and a fight for survival in another. The impacts of drought depend heavily on a nation's wealth, infrastructure, and reliance on agriculture.

In developed countries like the USA (California), impacts focus on commercial agriculture and economic losses. California's 2011–2017 drought cost the agricultural industry US$2.7 billion in 2015 alone, but there were near zero direct human deaths. This is due to high resilience, meaning the capacity of a community to withstand and recover from a hazard using wealth and technology like the Central Valley Project.

In emerging and developing countries like Ethiopia and Namibia, impacts are survival-based due to high vulnerability. In Ethiopia, 85% of the population relies on rain-fed subsistence farming, leaving them highly susceptible to crop failure. This forces massive rural-to-urban migration, with over 250,000 people per year moving to cities seeking survival. During the 2015 drought, 10.2 million people required emergency food aid, and school absentee rates hit 60% as children spent hours fetching water.

Despite these differences, there are clear similarities in how ecosystems are affected. Both regions suffered severe environmental degradation, including increased wildfire risk, loss of vegetation, and high tree mortality. Both also experienced rising food prices and a loss of ecological resilience.

Comparison of Drought Impacts

Impact Type	Developed Country (California, USA)	Emerging Country (Ethiopia/Namibia)
Social	Mandatory 25% urban water restrictions. Food prices for fresh produce rose by 6%.	435,000 children suffered Severe Acute Malnutrition. Disease outbreaks (cholera) due to contaminated water.
Economic	17,100 agricultural jobs lost. US$1.7 billion state economy cost in 2021.	40%–60% of livestock herds died. 50% to 90% of main crop production lost. Ongoing cost of US$1.1 billion per year.
Environmental	Over 100 million trees died. Groundwater over-extraction caused 60 cm of land subsidence.	Extreme desertification (Namibia lost 14.4 million acres of vegetation). High deforestation for fuelwood.

Analyzing Socio-Economic Data

How do geographers actually measure the true cost of a disaster? To understand why impacts differ, we must analyze quantitative data such as GNI per capita and the Human Development Index.

Developed countries face higher absolute economic losses (billions of dollars) but have low mortality rates. Emerging countries experience higher relative impacts, meaning the disaster destroys a larger percentage of their total wealth and causes severe food insecurity. Food security exists when all people have physical and economic access to sufficient, safe, and nutritious food.

Indicator	Developed (California, USA)	Emerging (Ethiopia)
GNI per capita	High (>US$60,000)	Low (~US$1,025 - US$1,350)
Human Development Index Rank	20th (Very High)	176th (Low)
Main Impact Focus	Economic and job loss	Famine, mortality, and disease
Vulnerability Type	Economically vulnerable	Socially and biologically vulnerable

Using Formulas to Analyze Data

In geography exams, you must be able to calculate the scale of these impacts using provided data.

1. Percentage Change Calculation This formula shows how much a value has grown or shrunk relative to its starting size.

$$\text{Percentage Change} = \frac{\text{New Value} - \text{Old Value}}{\text{Old Value}} \times 100$$

Worked Example:

If Namibia's crop yield fell from 500 tons to 150 tons during a drought, what is the percentage change?

• Step 1: Identify the values: Old Value = $500$, New Value = $150$.

• Step 2: Substitute into the formula: $\frac{150 - 500}{500} \times 100$

• Step 3: Calculate the difference: $-350$

• Step 4: Divide and multiply: $\frac{-350}{500} \times 100 = -70\%$

2. Growth Deficit Calculation Moderate to extreme droughts typically reduce GDP per capita growth by $0.39\%$ to $0.85\%$ globally. In Ethiopia, the 2015/16 drought caused a significant growth deficit.

$$\text{Growth Deficit} = \text{Target Growth} - \text{Actual Growth}$$

Worked Example:

Ethiopia projected a real GDP growth of $11.2\%$, but achieved only $8.0\%$ due to the drought.

• Step 1: Target Growth = $11.2\%$, Actual Growth = $8.0\%$.

• Step 2: $11.2\% - 8.0\% = 3.2\%$ deficit.

• This 3.2 percentage point loss represents billions of dollars in lost economic potential.

3. Water Deficit Calculation This formula helps determine the physical lack of water in an environment.

$$\text{Water Deficit} = \text{Precipitation} - \text{Potential Evapotranspiration}$$

For example, in California in 2021, a $3.5^\circ\text{F}$ temperature increase caused an extra 3–4 inches of evaporative demand, severely increasing the water deficit.

Despite the harsh economic data, Ethiopia's direct mortality rate in 2015 was much lower than during the 1984 drought. This was due to improved social resilience through the Productive Safety Net Programme and faster international aid.